Continuous motion packaging machines are known in the art. One common type of continuous motion packaging machine is an end loading machine which selects a predetermined number of articles, for example beverage containers, to include bottles and cans, and forms the articles into a desired product group size or configuration, for example six-packs, twelve-packs and full case lots of 24 article containers. Thereafter, the grouped articles are passed into a unitary container, such as pre-formed paperboard carton or sleeve for being packaged therein.
Many continuous motion packaging machines are constructed to have the flexibility to package various product or article group sizes or configurations on the same machine, depending on the desired packaging configuration of the articles, as well as on the size of the articles themselves and the article containers or cartons into which the articles will be passed. These machines typically use a selector device to group the articles and move them as a group toward and through the open end, or ends, of a pre-formed sleeve-type paperboard carton being moved on a carton transport conveyor in the direction of the path of travel at substantially the same speed and in substantially the same direction as the groups of articles being formed by the selector device. The carton transport conveyor is typically provided with a series of spaced and upstanding lugs along its length for forming a series of carton transport flights, or pockets, which sequentially move a spaced series of empty and erect cartons placed therein at an upstream carton opening station. The flights of the carton transport conveyor move in timed relationship with the formation of the groups of articles by the packaging machine selector device. The upstanding lugs of the carton transport conveyor are oftentimes provided with a fill block mounted thereon, the fill block being used in concert with the lug to move the empty and erect cartons, and later the filled cartons, along the path of travel toward a carton sealing station at which the end flaps of the carton will have glued and sealed on the open ends of the cartons.
In those continuous motion packaging machines which have the flexibility to package a variety of article sizes and groupings, the problem thus arises of being able to move the open end, sleeve-type paperboard cartons at high rates of speed in the direction of the path of travel without damaging the paperboard cartons, or allowing the paperboard cartons to become skewed so that the articles being transferred from the article selector device into the carton will jam, or will otherwise bridge across the selector device thus leading to machine shut down in order to remove the damaged and/or jammed paperboard cartons and/or articles. Moreover, another problem which is present in high speed continuous motion packaging machines results from the change of carton sizes as a result of the change in article size, in that it is difficult to employ one universal fill block to handle a variety of carton sizes. One common problem that arises with the use of a relatively short fill block, for example, when used with the relatively tall paperboard carton is that the top of the paperboard carton can lag behind the bottom of the carton carried between the upstanding lugs and fill blocks of the carton transport conveyor, so that the top of the carton trails behind the bottom of the carton, particularly when the carton is empty, so that the carton becomes skewed within the flight/pocket such that the bottom panel of the carton is lifted off of the article transport conveyor creating a step-up or lip between the surface of the conveyor formed as a part of the selector device and the bottom panel of the cartons so that the smooth transfer of articles from the selector device into the empty carton is prevented, which can result in damage to the carton, damage to the articles, as well as jamming of the selector device caused by the bridging of the articles within the flights of the selector device due to their inability to be moved into the empty paperboard cartons carried on the article transport conveyor.
In order to overcome this problem, therefore, removable fill blocks have been developed of varying height and configuration to be used with paperboard cartons of various article group sizings so that the paperboard cartons can be carried within the flights of the article transport conveyor while minimizing this carton flexing or skewing problem to ensure sustained machine efficiencies during high speed packaging operations. One example of such a removable fill block is disclosed in U.S. Pat. No. 5,546,734 to Moncrief, et al., issued on Aug. 20, 1996. FIGS. 10A, 10B, 10C, and 11 of Moncrief, et al. disclose a leading lug assembly in FIGS. 10B and 10C, and a trailing or pusher lug assembly in FIG. 10A. Each of the fill blocks of these two lug assemblies is constructed and arranged to be removably received on a pair of generally parallel guide pins formed as a part of each one of the respective flight lugs disclosed by Moncrief, et al. As shown in FIG. 10C of Moncrief, et al., the bottom end of the fill blocks has a lower mating slot adapted to be received on the lower one of the guide pins on the rotating lug, so that the fill block can then be pivoted about the lower mating slot while an upper mating slot is urged into engagement with the upper rotating lug in order to hold the fill block on the retaining lug with a snap fit. So constructed, these fill blocks may be easily removed and replaced in order to provide fill blocks of varying configurations for use with varying article group size configurations, and thus carton sizes.
One problem that has arisen with the use of this type of fill block, however, is that fill blocks which can be easily removed and replaced from a flight lug can also be knocked off, or fall off, of the flight lug during packaging operations, and/or machine adjustment, i.e. removing damaged articles or containers, or removing jammed articles from the machine. This can occur when machine technicians lean over the article transport conveyor and accidentally strike the flight lugs, and thus the fill blocks, with their bodies. In addition, as an average article transport conveyor may have somewhere in the range of 200 or more flight lugs and fill blocks, cost dictates that the fill blocks cannot be machined to exact tolerances so that a "tight" snap fit is obtained as opposed to a "snug" snap fit, which thus allows for the cost efficient manufacture of fill blocks which are easy to remove and replace, but which are also easy to be inadvertently knocked off the flight lugs. In addition, the possibility exists that these fill blocks may be thrown off by the article transport conveyor itself as the flight lugs and the fill blocks pass over the end sprockets of the conveyor chain during operation of the article transport conveyor. As the flight lugs and fill blocks pass over the end sprockets, they do so at a greater angular rate of speed than the base of the flight lug connected to the conveyor chain, with the result that once the flight lug and fill block assembly rounds the sprocket and enters a return chain raceway, for example, an induced torque will occur in the fill block on the flight lug as the angular speed of the flight lug assembly decelerates to the linear speed of the conveyor chain with the result that this torquing can throw this type of fill block off of the flight lug, which in turn will result in carton skewing, and machine jamming should the flight lug be returned into a carton transport position without an accompanying fill block designed for that particular paperboard carton being moved along the path of travel.
What is needed, therefore, but seemingly unavailable in the art is a flight lug assembly adapted for use in the article transport conveyors of continuous motion packaging machines which provides flexibility, yet which will ensure that the fill blocks remain mounted on the flight lugs of the transport conveyor. More particularly, what is needed is a flight lug assembly having a removable fill block which can be easily removed and replaced, yet which can be locked to the flight lug of the assembly to prevent the fill block from being accidentally knocked off of the flight lug, or be thrown off of the flight lug, during machine adjustment, repair, and operation. What is also needed is a simple device which accomplishes these tasks but yet is adapted for use with a wide range of articles, packaging configurations, and carton sizes. Thus, what is needed but currently unavailable in the art is a simple and efficient flight lug assembly having fill blocks which can be easily removed and replaced in accordance with the requirements of the packaging machine operation, yet which can be locked to the flight lugs so that they are not otherwise removed from the flight lug when their removal is not intended in order to satisfy the demands for flexibility, and high production rates needed in the use of continuous motion packaging machines in high volume packaging operations.